Daniel Amoils

Black holes are some of the most extreme objects in the universe. They are regions of space where gravity is so strong that nothing, not even light can escape. Black holes were first predicted by the theory of General Relativity., which also describes their properties and behavior. It is predicted that a black hole can be fully described by just two properties, which are its mass and its spin. In General Relativity, the geometry of the space around a black hole can be described using the Kerr metric. The Kerr metric takes in the mass and spin of a black hole and returns the shape of the space around the black hole. The accuracy of General Relativity can be tested by looking for deviations from the shape of the region around the black hole compared to what is described in the Kerr metric. This can be difficult because black holes are far away from us and absorb all the light that falls into them.

Some black holes are surrounded by an accretion disk, which is a disk of matter that spins around a black hole before it falls into it. The matter in this disk is very bright, which allows us to measure and study the light from the disk. The light from this disk can be used to learn about the region around the black hole. This can then be compared to the predicted shape in order to see if it matches. This provides a test of General Relativity allowing us to further our understanding of gravity. 

I will be using NuSTAR X-ray data on the black hole named MAXI J1820+070. This black hole is a good one to use because its accretion disk is very bright, making it easier to test using my mentor’s model. I will need to find what black hole parameters, such as mass, spin, and inclination angle, best match the data using a program called XSPEC. Then I will use my mentor’s model to measure the deviations from the Kerr metric.